feat: use DocsFilter

[forshev]

Description

Use DocsFilter struct in search and fetch

Fixes #290

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[cheb0]

@seqbenchbot up main search-keyword-exact-match-warm

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[cheb0]

@seqbenchbot up main search-keyword-exact-match-warm

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[cheb0]

@seqbenchbot down 76b796bf

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Nice, @cheb0 <(-^,^-)=b!

The benchmark with identificator 76b796bf was finished.
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Query	Type	mean (ms)			stddev (ms)			p(50) (ms)			p(95) (ms)			p(99) (ms)			iterations
		base	comp	diff	base	comp	diff	base	comp	diff	base	comp	diff	base	comp	diff	base	comp	diff
bulk	warm	67.31	68.69	+2.05%	23.91	26.49	+10.79%	61.00	61.00	0.00%	116.50	124.00	+6.44%	151.50	157.50	+3.96%	2450.00	2450.00	0.00%
service:payment-backend-eu AND k8s_namespace:prod	warm	120.96	122.50	+1.28%	112.08	111.98	-0.09%	99.00	105.00	+6.06%	232.00	234.00	+0.86%	758.50	748.50	-1.32%	7652.00	7407.00	-3.20%

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[dkharms]

A few comments on files outside the PR diff:

Fraction Refresh

DocsFilter.RefreshFrac is called only after the active fraction is sealed. It re-runs the entire document filtering process, but at that point only LID remapping is necessary.

Issue with Active fraction

I'd consider this a corner case, but it's worth raising. We can receive out-of-order documents (for example, with timestamps several hours before ingestion time), and such documents become available for search and fetch immediately.

It seems DocsFilter should have a separate goroutine that masks data in the active fraction until it is sealed. Otherwise, when a new active fraction is created, func (df *DocsFilter) processFilter(filter *Filter, fracs fracmanager.List) may outpace the write rate.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 70.65217% with 135 lines in your changes missing coverage. Please review.
✅ Project coverage is 71.44%. Comparing base (c9dd219) to head (27e61d1).

Files with missing lines	Patch %	Lines
skipmaskmanager/skip_mask_manager.go	64.91%	77 Missing and 23 partials ⚠️
cmd/seq-db/seq-db.go	0.00%	15 Missing ⚠️
frac/active_index.go	90.69%	2 Missing and 2 partials ⚠️
skipmaskmanager/encoding.go	57.14%	2 Missing and 1 partial ⚠️
cache/cache.go	75.00%	1 Missing and 1 partial ⚠️
frac/processor/fetch.go	33.33%	1 Missing and 1 partial ⚠️
frac/processor/search.go	77.77%	1 Missing and 1 partial ⚠️
frac/sealed_index.go	93.75%	1 Missing and 1 partial ⚠️
storeapi/store.go	75.00%	1 Missing and 1 partial ⚠️
skipmaskmanager/iterator_asc.go	0.00%	1 Missing ⚠️
... and 2 more

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #372      +/-   ##
==========================================
+ Coverage   70.11%   71.44%   +1.32%     
==========================================
  Files         219      219              
  Lines       16288    16454     +166     
==========================================
+ Hits        11420    11755     +335     
+ Misses       4030     3827     -203     
- Partials      838      872      +34     

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